It is a common practice to enter information on digital forms in order to promote paperless procedures. A problem arises when a seal needs to be affixed on a digital form. In such a case, typically a seal is affixed on paper, then the seal is scanned with a scanner to acquire an image of the seal, and the image is put on the digital form. However, true paperless cannot be achieved by this method.
It has been conventionally known to pick a seal impression by directly taking an image of a seal-impression face (the face of a seal) with a TV camera. However, there is a problem that, when the face of a seal is ordinarily photographed, it is not possible to discriminate between a character part and a carved part on the face of the seal with high accuracy.